STABLE FREQUENCY SWEEP OF FREQUENCY VARIABLE LASER

摘要

PURPOSE:To enable stable frequency sweep of a frequency variable laser by a method wherein the light of the laser is detected in a lock-in amplifier after passing through a reference gas cell, the output is compared with a reference voltage to make an error signal and the feedback of the error signal is applied to the laser. CONSTITUTION:Part of a laser beam is sent to a reference gas cell 4 using a beam splitter 3. The laser beam sent out from the cell 4 is condensed in the sensible part of a detector 5. The output of the detector 5 reaches to a lock-in amplifier 6. The absorption spectral line of the reference gas is subjected to phase sensitive detection in a laser modulation frequency. The output L of the amplifier 6 is sent to a differential amplifier 7. A reference voltage generator 8 makes chopping waves R. The amplifier 7 compares the 1 with the R to make an error signal. This error signal is fed back to a diode laser power source 9. Thereby, the frequency of a diode laser 1 can be swept stably.